1. Field of the Invention
The present invention relates to the temporary storage of articles which are being transported between successive processing stations. More specifically, this invention is directed to a storage device for temporarily receiving rectangular packages, which are being transported by means of a conveyor belt from a source station to a receiving station, and for returning the stored packages to the conveyor belt as required. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Description of the Prior Art
In the manufacture of many products it is common to transport the partially completed product between work stations by means of a system of conveyor belts. Since there may be periods of time when the equipment at either the upstream or downstream station is not operating, it is known to provide devices for receiving the articles from the conveyor and storing such articles for subsequent return to the conveyor. Thus, if the downstream processing machine is stationary, the storage device must receive packages which are being discharged from the machinery at the previous work station. Conversely, if the supply of articles from the previous work station is temporarily interrupted, the storage device must return articles to the conveyor so that the downstream processing station will receive a constant supply. In order to be in readiness for both functions, the storage device should be approximately half filled under normal operating conditions.
Storage devices of the type generally described above are known in the art. In one form of such storage device the articles removed from the conveyor system are stacked upon one another. An example of such a stacking type storage device may be seen from German patent specification No. 1,456,503. While such stacking type storage devices have utility, they cannot be employed with articles which may be crushed such as, for example, soft cigarette packages since the pressure exerted on the packages of the lowest layer may be excessive.
Another type of prior art storage device comprises an endless circulating belt or chain which carries storage cells. The articles being temporarily diverted from the conveyor system are inserted into these storage cells. An example of this type of storage device may be seen from British patent specification No. 1,475,773. Storage devices of the endless circulating belt or chain type have the disadvantage that complicated and thus costly mechanisms are required to achieve the insertion and removal of rows of packages from the cells.
In order to avoid the expense and complexity of the previously known endless circulating belt type storage device, it has been proposed to provide storage devices in which a storage belt itself undertakes the removal from and insertion of rows of articles on the conveyor. A storage device of this type may be seen from published German patent specification Ser. No. 26 40 867. Storage devices of the type shown in German patent application Ser. No. 26 40 867 have the disadvantage of requiring a relatively large amount of space and this space requirement, in turn, interfers with the monitoring of the apparatus since the view of supervisory personnel is completely or partially blocked. In order to reduce the size of the apparatus, as shown in published German patent application Ser. No. 24 02 855, it has been proposed to store rows of articles in a number of side-by-side and one-above-another storage cylinders. It has been found, however, that the use of such storage cylinders, in the case of soft cigarette packages, results in excessive stresses being imposed on the packages by the constant transferring of the packages from one storage cylinder to another.
A further possibility of providing for the volumetrically efficient temporary storage of articles removed from a conveyor is described in published German patent application Ser. No. 30 25 527. In the apparatus of German application Ser. No. 30 25 527 rows of packages are placed on individual carrier elements and the separation between these carrier elements is made variable so that, at the receiving or removal location, there is sufficient space to move the packages while, in the storage location, the packages or other articles are positioned close to one another. However, the provision of such relatively movable individual carrier elements results in a costly mechanical system and the space required for the storage device remains relatively large which, as noted above, is undesirable.